The Lean Startup: How Today's Entrepreneurs Use Continuous Innovation to Create Radically Successful Businesses · chapter 10 · id the-lean-startup-c10-05-for-the-paid-engine-of-growth-

“For the paid engine of growth, the key formula is simple: customer acquisition cost (CAC) must be less than customer lifetime value (LTV) for sustainable growth. A positive marginal profit per customer funds further acquisition.”

needs contextconfidence: medium⚠ extracted by pipeline, re-audit pending

Receipts

David Skok, SaaS Metrics -- CAC/LTV Framework (2010)source alive

Skok's CAC/LTV framework, published in 2010 before Ries' book, provides more detailed guidance including the 3:1 LTV/CAC ratio benchmark and payback period calculations.

Gupta & Lehmann (2005), Managing Customers as Investments, Journal of MarketingFLAGGED: DOI not in registry

Customer lifetime value models and their relationship to acquisition costs were formalized in marketing science well before 2011. The CAC < LTV principle is a basic unit economics concept, not a lean startup innovation.

WSJ -- Money-Losing Startup Era Over (2023)paywalled — manual check queued

Many startups that followed lean startup principles ignored CAC/LTV discipline for years, burning billions on growth before unit economics turned positive (or never did). WeWork, Uber, DoorDash are prominent examples.

This claim is a stable, citable object. If you can falsify a verdict, tell us — corrections are loud here.